FIRE-WORKS

may be divided into three kinds, the cla ification depending chiefly on the method of setting them off or firing them. Some are fired whilst held in the hand, or set off on the ground; others, such as rockets, are projected by the aid of a small explosive carried within themselves, and explode in the air. Others, heavier and more showy, stich as shells, are projected from a small grenade or mortar, similar to a trench mortar. Lastly there are what is known as ‘set-pieces’ or fire-work pictures, which comprise fire-works representing water-falls, portraits, mottoes, erests, aeroplanes, or any special design desired. Amongst fire-works of the first kind may be mentioned rockets, wheels or whirligigs, and Bengal lights. Rockets are charged on what is known as the spindle system, a long steel needle penetrating the paper tube that holds the charge. After the tube has been filled, and the spindle withdrawn, a cavity remains, which after the explosion becomes filled with the expanded air, causing the ascent of the rocket.: The composition contained in the upper part of the paper tube is so) arranged as to make it burst at the) proper altitude, and scatter the stars! with which it is filled. | Shells are made of a kind of papier' mdché consisting of layers of paper and calico compre ed into the shape of a bow] until they are as hard as iron. | Two of these bowls are filled with large/ stars and joined together, then covered with canvas. They are fired from a small mortar, and the expelling explosion ignites a fuse connected witb a/ time-fuse inside the shell, causing the! shell to burst and ignite the stars. The following are some of the in-) gredients used: oxalate of soda, us| antimony, nitrate of lead, picrate of ammonia, subchloride of copper, and carbonate of strontia. Methylated spirits are frequently used in mixing, colours. Iron filings make wonderful coruscations, and are used to represent! falls and cascades. Steel filings are also used with even better effect. With set-pieces any design can be produced in outline. The subject is first set out on squared paper, and scaled, and it is then transferred to a frame, which is divided into small squares. The design is traced with small bamboo canes which bend easily, and can be made to follow the design. Small fire-works on the rocket principle are fastened to the frame-work; these are called lances and gerbs. A lance is a small paper tube filled with a composition and priming on top; this is used for small devices, such as crests, mottoes, . A gerb is*much larger, and filled in certain proportions with a 451 FIRKIN composition of sulphur, saltpetre, and charcoal, a colouring mixture being added. ‘This is used for large produc-’ tions. Part of the manufacture of gerbs is called coning. Cones are attached to them containing salts of various metals, sodium giving a yellow light, caleium a red, strontium a crimson, and barium a green, and these produce the colour effect on the set piece. The lances and gerbs are glued perpendicularly to the canes which trace the outiine desired. They are then attached to a fuse, which is a piece of cotton soaked in a liquid composition, dried, and enclosed ina paper tube. When a port-fire is applied to the end of this fuse or quick-match, the ignition is instantaneous over the whole set-piece. Magnesium powder and lycopodium are used for giving lightning eifects in stage pieces. Life-saving rockets carry a line from the shore to a wrecked ship, or from ship to shore. FK ire-works are much used for signalling purposes. Rockets and ground-flares played a big part in the European War, and were used as signals everywhere. The 5.0.8. was usually a combination of coloured rockets, commonly known as Very lights, which were fired from a specially made pistol.